The accident happened on Thursday afternoon as the terminal in Ba Ria – Vung Tau Province, 80 km southeast of Ho Chi Minh City, was receiving heavy rains.
The ship Wan Hai A02 stretching 335 m long, 51 m wide, and having a loading capacity of 140,000 tons drifted out of its navigational channel when reaching a bending area on Thi Vai River near the terminal.
As a result, its left side collided and pressed on to the right side of Vassos 2, a cargo ship that was docked at the terminal's wharf.
Wearing the Cyprus flag, Vassos 2 stopped at the terminal to unload goods.
The collision caused no fatalities but Vassos 2 hit the dock and as a result, a 46m-long section of the dock collapsed.
Part of the conveyor belt system sunk into the water.
Authorities are assessing the damage and extracting security cameras and anemometers as well as collecting relevant data to clarify the cause.
Cai Mep - Thi Vai is one of the 20 largest ports in the world.
The cluster has 35 ports in total and 22 of them have been put into use with a total capacity of 117.8 million TEUs per year, including seven ports specializing in serving container ships with a total capacity of 6.8 million TEUs per year.